643669 has 8 divisors (see below), whose sum is σ = 704480. Its totient is φ = 584496.

The previous prime is 643661. The next prime is 643681. The reversal of 643669 is 966346.

643669 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643669 - 2³ = 643661 is a prime.

It is a super-2 number, since 2×643669² = 828619563122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643669.

It is not an unprimeable number, because it can be changed into a prime (643661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502 + ... + 1240.

It is an arithmetic number, because the mean of its divisors is an integer number (88060).

2⁶⁴³⁶⁶⁹ is an apocalyptic number.

It is an amenable number.

643669 is a deficient number, since it is larger than the sum of its proper divisors (60811).

643669 is a wasteful number, since it uses less digits than its factorization.

643669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819.

The product of its digits is 23328, while the sum is 34.

The square root of 643669 is about 802.2898478729. The cubic root of 643669 is about 86.3417535089.

The spelling of 643669 in words is "six hundred forty-three thousand, six hundred sixty-nine".